JP2022149035A - Wavelength conversion member and light-emitting device - Google Patents

Abstract

To provide a wavelength conversion member and a light-emitting device which are capable of inhibiting deterioration of emission performance due to temperature extinction of a wavelength conversion member, etc. and of phosphor even when a high output light-emitting element is used.SOLUTION: A wavelength conversion member 100 comprises: a tabular substrate 110; a phosphor layer 120 provided on one principal surface 112 of the substrate 110 and formed of phosphor particles 122 and a light transmissive ceramic 124; and a cooling member 130 provided on the other principal surface 114 of the substrate 110 and including a space 134 storing coolant therein. The cooling member 130 cools the substrate 110 or the phosphor layer 120 by bringing the coolant into contact with the other principal surface 114 of the substrate 110.SELECTED DRAWING: Figure 1

Description

The present invention relates to wavelength conversion members and light emitting devices.

2. Description of the Related Art A light-emitting device using a wavelength-converting member that emits light emitted from a light source such as a light-emitting element such as an LED (Light Emitting Diode) or an LD (Laser Diode) as light having a different wavelength converted by a phosphor layer is known. there is In recent years, there has been an increasing number of applications using LDs as light sources, which have high energy efficiency and can easily respond to miniaturization and high output.

As the output of such a light-emitting element increases, the light source itself and the wavelength conversion member to be irradiated by the light source generate heat, which may cause a problem of deterioration in the performance of the light-emitting device.

Patent Document 1 discloses that a mounting substrate on which an LED chip is mounted is coated with fluid from a A light-emitting device is disclosed in which a flow path for passing a coolant is formed.

Patent Document 2 discloses a light conversion member containing a light-emitting element and a fluorescent material that absorbs at least part of the light from the light-emitting element and emits light having a different wavelength. , discloses a light-emitting device having a heat-dissipating member on the side of the light-converting member when viewed from the light-emitting element.

Patent Document 3 discloses a light-emitting diode package for the purpose of highly efficient heat dissipation, which includes a case member covering a light-emitting diode mounted on a substrate, a liquid coolant inside the case member, and fluorescent light dispersed in the coolant. It is disclosed to comprise body particles.

Japanese Patent Application Laid-Open No. 2007-088078 JP 2005-294185 A JP 2008-004689 A

According to the configuration of Patent Literature 1, even if the temperature of the LED chip rises due to heat generated during light emission, a decrease in light output of the LED chip itself is suppressed. However, deterioration in performance due to heat generation of the wavelength conversion member itself that receives light from the light emitting element has become a problem as the output of the light emitting device has increased, and Patent Document 1 does not disclose cooling of the wavelength conversion member. .

According to the configuration of Patent Document 2, the heat dissipation property of the wavelength conversion member that receives the light from the light emitting element is improved, and deterioration in performance as a light emitting device is suppressed. The material of the heat dissipation member in Patent Document 2 is a material that can transmit at least the light from the light emitting element, or a material that can transmit both the light from the light emitting element and the light emitted from the light conversion member. It is described that there is, and quartz glass is used in the examples. However, quartz glass has a low thermal conductivity, and it may not be sufficient as a countermeasure against heat generation of the wavelength conversion member accompanying the increase in the output of the light emitting element.

According to the configuration of Patent Document 3, the heat generated from the LED chip is received by the coolant, heat convection occurs in the coolant within the case member, and the heat is dissipated into the atmosphere. However, since the phosphor particles dispersed in the case member are always exposed to the coolant environment, there is concern about damage and deterioration of the phosphor particles.

The present invention has been made in view of such circumstances, and is capable of suppressing deterioration in light emission performance due to temperature quenching of a wavelength conversion member even when a high-output light emitting element is used, and is capable of An object of the present invention is to provide a wavelength conversion member and a light emitting device capable of suppressing deterioration.

(1) In order to achieve the above object, the wavelength conversion member of the present invention is a wavelength conversion member comprising a substrate formed in a flat plate shape, provided on one main surface of the substrate, and containing a phosphor a phosphor layer formed of particles and translucent ceramics; and a cooling member provided on the other main surface of the base material and having a space for storing a coolant therein, wherein the cooling member comprises the The base material or the phosphor layer is cooled by bringing a coolant into contact with the other main surface of the base material.

In this way, since the coolant contacts the main surface opposite to the main surface on which the phosphor layer is formed, the base material and the phosphor layer can be cooled via the coolant. However, deterioration of the light emission performance due to temperature quenching of the wavelength conversion member can be suppressed, and deterioration of the phosphor can be suppressed because the phosphor layer does not come into contact with the coolant.

(2) Further, in the wavelength conversion member of the present invention, the base material is characterized by having translucency.

Thereby, a transmissive wavelength conversion member can be constructed. In the transmissive wavelength conversion member, since there is a high possibility that the phosphor at a position close to the base material irradiated with the light of the light emitting element first generates more heat, The cooling effect can be further enhanced by contacting the main surface of the coolant.

(3) In the wavelength conversion member of the present invention, the cooling member includes a first member forming a bottom surface facing the substrate and a second member forming a side surface connected to the substrate. At least a part of the first member is translucent.

As a result, the light-emitting element can be arranged outside the cooling member, contact between the light-emitting element and the coolant can be prevented, and the risk of deterioration or failure of the light-emitting element can be reduced.

(4) Further, in the wavelength conversion member of the present invention, the cooling member includes a first member forming a bottom surface facing the substrate and a second member connected to the substrate and forming a side surface. In addition, the second member is characterized by not having translucency.

As a result, light can be prevented from leaking in an unintended direction from the side surface of the cooling member in the transmissive wavelength conversion member.

(5) Further, in the wavelength conversion member of the present invention, the cooling member has a supply hole for supplying the coolant to the space and a discharge hole for discharging the coolant from the space, and the supply hole and the discharge A supply pipe and a discharge pipe through which the coolant passes are connected to the holes, respectively, and the cooling member cools the base material or the phosphor layer by allowing the coolant to flow through the space through the supply pipe and the discharge pipe. It is characterized by

By circulating the coolant stored in the space in this way, the cooling effect can be further improved, and it is possible to cope with the increase in output of the light emitting element.

(6) Further, a light-emitting device of the present invention is a light-emitting device, comprising: the wavelength conversion member according to any one of the above (1) to (5); and a light-emitting element that emits light having a wavelength within a specific range.

As a result, it is possible to construct a light-emitting device in which a wavelength conversion member having a high cooling effect and a light-emitting element are combined, and it is possible to cope with an increase in output of the light-emitting element.

ADVANTAGE OF THE INVENTION According to this invention, even if it uses a high-power light emitting element, it can suppress the deterioration of the light emission performance by the temperature quenching of a wavelength conversion member, etc., and can suppress deterioration of a fluorescent substance.

It is a typical sectional view showing an example of a wavelength conversion member concerning a 1st embodiment. It is the schematic diagram which expanded the cross section of the fluorescent substance layer part of the wavelength conversion member. It is a typical perspective view showing an example of a wavelength conversion member concerning a 1st embodiment. It is a typical sectional view showing a modification of a wavelength conversion member concerning a 1st embodiment. 7A and 7B are schematic cross-sectional views each showing a modification of the wavelength conversion member according to the first embodiment; FIG. FIG. 5 is a schematic cross-sectional view showing an example of a wavelength conversion member according to a second embodiment; 4A to 4C are schematic cross-sectional views each showing an example of a light-emitting device using the wavelength conversion member according to the first embodiment; FIG. It is a flowchart which shows an example of the manufacturing method of the wavelength conversion member of this invention. It is typical sectional drawing which shows the wavelength conversion member of an Example, respectively (a), (b). It is a typical sectional view showing a wavelength conversion member of a comparative example.

Next, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in each drawing, and overlapping descriptions are omitted. In addition, in the configuration diagram, the size of each component is conceptually represented, and does not necessarily represent the actual size ratio.

[First Embodiment]
[Structure of Wavelength Conversion Member]
FIG. 1 is a schematic cross-sectional view showing an example of the wavelength conversion member according to the first embodiment. FIG. 2 is an enlarged schematic diagram of the cross section of the phosphor layer portion of the wavelength conversion member. FIG. 3 is a schematic perspective view showing an example of the wavelength conversion member according to the first embodiment. A wavelength conversion member 100 according to this embodiment includes a base material 110 , a phosphor layer 120 and a cooling member 130 .

The wavelength conversion member 100 transmits or reflects incident light emitted from a light source, and is excited by the incident light to generate light of different wavelengths. For example, the incident light of blue light is transmitted or reflected, and the converted light of green, red, or yellow converted by the phosphor layer 120 is emitted, and the converted light and the incident light are combined, or only the converted light is emitted. It can be used and converted into various colors of light.

The base material 110 is formed in a flat plate shape. The shape of the main surface of the substrate 110 may be various shapes such as square, polygon, circle, and ellipse depending on the light emitting device used. Also, the substrate 110 may be formed with a recess in which the phosphor layer 120 is formed. Since the thickness of the phosphor layer 120 is sufficiently thinner than the thickness of the base material 110, the base material 110 in which the recesses are formed is also considered to be flat. For example, the thickness of the substrate 110 is preferably 0.5 mm to 2 mm.

Glass, sapphire, aluminum, iron, copper, or the like can be used as the material of the base material 110 . The transmissive wavelength conversion member 100 is manufactured with the base material 110 made of a translucent material. In the reflective wavelength conversion member 100, the base material 110 can be entirely made of a material that reflects light. may be provided as a reflective layer, or a reflection-increasing film such as TiO ₂ may be formed.

The substrate 110 preferably has a high thermal conductivity in order to efficiently transfer the heat generated in the phosphor layer 120 irradiated with high-energy light source light to the cooling member 130 . Therefore, in the case of a transmissive type, it is preferable to use sapphire. In the case of a reflective type, it is preferably made of aluminum or copper.

The base material 110 preferably has translucency. Thereby, the transmissive wavelength conversion member 100 can be configured. In the transmissive wavelength conversion member 100, the phosphor layer 120 is formed because there is a high possibility that the phosphor particles 122 at positions close to the substrate 110 irradiated with the light of the light emitting element first generate more heat. The cooling effect can be further enhanced by bringing the refrigerant into contact with the main surface 112 and the opposite main surface (the other main surface 114). At this time, a dichroic mirror coat may be formed on the surface of the substrate 110 to transmit light from the light source and reflect converted light.

Phosphor layer 120 is provided on one main surface 112 of substrate 110 . The phosphor layer 120 is composed of phosphor particles 122 and translucent ceramics 124 . The translucent ceramics 124 bonds the phosphor particles 122 together and bonds the phosphor particles 122 and the substrate 110 together. As a result, since it is bonded to the base material 110 that functions as a heat dissipation material, heat can be efficiently dissipated against the irradiation of high energy density light, and the heat generated during light conversion in the phosphor layer 120 accumulates, resulting in a temperature rise. Quenching can be suppressed.

If a concave portion is formed on one main surface 112 of substrate 110, phosphor layer 120 may be provided in the concave portion. As a result, the contact area between the substrate 110 and the phosphor layer 120 can be increased, so that heat dissipation can be further improved. The thickness of the phosphor layer 120 may be thicker or thinner than the depth of the recess.

The thickness of phosphor layer 120 is preferably 15 μm or more and 300 μm or less, and more preferably 50 μm or more and 200 μm or less. If the phosphor layer 120 is too thin, there will be a portion where the presence of the phosphor particles 122 is thin in the optical path, which may make it impossible to obtain the necessary converted light. On the other hand, if it is too thick, there is a possibility that the phosphor layer 120 may accumulate heat and deteriorate its characteristics.

The thickness of the phosphor layer 120 can be measured by analyzing a SEM image of a cross section perpendicular to the planar direction of the substrate 110 . For the above cross section, an SEM cross-sectional photograph is taken at a magnification of 1000 times, for example, 10 perpendicular lines are drawn at equal intervals of 20 μm, and the top surface of the substrate 110 (one main surface) is drawn from the top surface of the phosphor layer 120 112) is measured, and the average value of the lengths of the 10 lines is taken as the thickness of the cross section. It is preferable to take a plurality of cross-sectional SEM images so as to represent the average thickness of the entire phosphor layer 120 . For example, images are taken at three or more locations at random, and the average thickness of each cross section is taken as the thickness (average thickness) of the phosphor layer 120 .

The phosphor layer 120 may contain inorganic particles in addition to the phosphor particles 122 and the translucent ceramics 124 . When inorganic particles are mixed, inorganic particles for various purposes can be mixed. For example, the purpose of adjusting the viscosity of the phosphor paste, the purpose of adjusting the density of the phosphor particles in the phosphor paste, the purpose of scattering light with the phosphor layer, the purpose of improving the thermal conductivity of the phosphor layer, the phosphor For example, the purpose is to reduce the voids in the layer. The average particle size of the inorganic particles is preferably equal to or smaller than the average particle size of the phosphor particles contained in phosphor layer 120 .

The average particle diameter of the phosphor particles 122 is preferably 5 μm or more and 50 μm or less, more preferably 7 μm or more and 30 μm or less. When the thickness is 5 μm or more, the emission intensity of the converted light is increased, and the emission intensity of the wavelength conversion member 100 is increased. Further, when the thickness is 50 μm or less, the thickness of the phosphor layer 120 can be easily adjusted, and the risk of shedding of the phosphor particles 122 can be reduced. Also, the temperature of each phosphor particle 122 can be kept low, and temperature quenching can be suppressed. In addition, in this specification, an average particle diameter is a median diameter (D50). The average particle size can be measured using a dry measurement or a wet measurement with a laser diffraction/scattering particle size distribution analyzer.

For the phosphor particles 122, for example, an yttrium-aluminum-garnet-based phosphor (YAG-based phosphor) and a lutetium-aluminum-garnet-based phosphor (LAG-based phosphor) can be used. In addition, the phosphor particles 122 can be selected from the following materials according to the design of the color to be emitted. For example, blue phosphors such as _BaMgAl10O17 :Eu, _ZnS :Ag,Cl, _BaAl2S4 :Eu or _CaMgSi2O6 : _Eu , _Zn2SiO4 :Mn, ₍ Y _, Gd) _BO3 : Tb, ZnS: Cu, Al, (M1) _2SiO4 :Eu, ₍ M1)(M2)2S:Eu _, (M3) _3Al5O12 :Ce, _SiAlON :Eu, _CaSiAlON :Eu, (M1) Yellow or green phosphors such as _Si2O2N :Eu or ₍ Ba, Sr, Mg) _2SiO4 :Eu, Mn, yellow such as ₍ M1) _3SiO5 :Eu or ₍ M1)S:Eu, orange or red phosphors, (Y,Gd) _BO3 :Eu, _Y2O2S :Eu, ₍ M1) _2Si5N8 :Eu _{, (} M1) _AlSiN3 :Eu or _YPVO4 :Eu Examples thereof include red-based phosphors. In the above chemical formula, M1 includes at least one of the group consisting of Ba, Ca, Sr and Mg, M2 includes at least one of Ga and Al, and M3 includes Y, Gd, At least one of the group consisting of Lu and Te is included. The phosphor particles 122 described above are merely examples, and the phosphor particles 122 used in the wavelength conversion member 100 are not necessarily limited to those described above.

The translucent ceramics 124 is formed by hydrolyzing or oxidizing an inorganic binder, and is made of a translucent inorganic material. The translucent ceramics 124 is composed of, for example, silica (SiO ₂ ) and aluminum phosphate. Since the translucent ceramics 124 is made of an inorganic material, it does not deteriorate even if it is irradiated with high-energy light from a laser diode or the like. In addition, since the translucent ceramics 124 has translucency, it can transmit light source light and converted light. Ethyl silicate, an aqueous solution of primary aluminum phosphate, and the like can be used as the inorganic binder.

In addition, a substance with translucency is the radiation of light that escapes from the opposite side when light in the visible light wavelength range (λ = 380 to 780 nm) is vertically incident on a target substance of 0.5 mm. A substance that has the property that the flux exceeds 80% of the incident light.

The cooling member 130 is provided on the other main surface 114 of the base material 110 and has a space 134 for storing a coolant therein. Cooling member 130 cools substrate 110 or phosphor layer 120 by contacting the other main surface 114 of substrate 110 with a coolant.

Cooling member 130 is preferably formed in a bottomed opening shape. By covering the opening 136 of the cooling member 130 with the base material 110 , the space 134 is sealed and the coolant can be brought into contact with the other main surface 114 of the base material 110 . The shape of the cooling member 130 may be any shape as long as it allows the coolant to contact the other main surface 114 of the base material 110 . Although the thickness of cooling member 130 is not particularly limited, it is preferably 0.5 mm or more in order to reduce the risk of damage to cooling member 130 due to internal pressure. Cooling member 130 may be provided with cooling fins.

The connection method (fixing method or joining method) between the cooling member 130 and the base material 110 may be any method such as screwing, clamping, bonding with an adhesive, etc., as long as the method can prevent refrigerant leakage due to internal pressure. It can be a method. A gasket such as an O-ring 140 may also be used. Moreover, you may use these together. When an adhesive is used, it preferably has high thermal conductivity, and for example, it is preferable to use a silicone adhesive containing silicone resin. FIG. 4 is a schematic cross-sectional view showing a modification of the wavelength conversion member according to the first embodiment. FIG. 4 shows an example using an O-ring 140 and screwing. 4 shows an example in which the phosphor layer 120 is formed in a concave portion of the base material 110. As shown in FIG.

The cooling member 130 may be formed by one member, or may be formed by combining a plurality of members. FIGS. 5A and 5B are schematic cross-sectional views showing modifications of the wavelength conversion member according to the first embodiment, respectively. As shown in FIGS. 5A and 5B, the cooling member 130 includes a first member 131 forming a bottom surface facing the substrate 110 and a second member 131 forming a side surface connected to the substrate 110 . of the member 132 may be provided. Moreover, you may comprise using members other than these.

The cooling member 130 includes a first member 131 forming a bottom surface facing the substrate 110 and a second member 132 forming a side surface connected to the substrate 110. The first member 131 has at least one It is preferable that the part has translucency. As a result, the light emitting element can be arranged outside the cooling member 130, contact between the light emitting element and the coolant can be prevented, and the risk of deterioration or failure of the light emitting element can be reduced. For example, sapphire, glass, or the like can be used as the substance having translucency.

The cooling member 130 includes a first member 131 forming a bottom surface facing the substrate 110 and a second member 132 connected to the substrate 110 and forming a side surface. It is preferred that it has no properties. As a result, light can be prevented from leaking in an unintended direction from the side surface of the cooling member 130 in the transmissive wavelength conversion member 100 .

As the non-translucent member, for example, ceramics, metal, resin (composite resin containing high thermal conductivity filler material, etc.), etc. can be used. Further, a layer for preventing light transmission may be formed on the surface of the substrate having translucency.

The second member 132 is preferably made of a metal member. In this way, since the second member 132 is formed of a metal member, it has excellent thermal conductivity, and the heat generated in the phosphor layer 120 is transferred directly to the second member 132 through the base material 110 or to the coolant. Since it is possible to radiate heat from the second member 132 from the second member 132, it is possible to suppress the deterioration of the light emission performance due to temperature quenching etc. as the wavelength conversion member 100, and it is possible to easily respond to the increase in the output of the light emitting element. can.

Aluminum, copper, iron, and alloys thereof can be used as the metal member, and the light source light passing through the space and the converted light that is wavelength-converted and emitted toward the second member 132 are further reflected and returned. Considering this, it is particularly preferable to use aluminum, which has a high reflectance in the entire visible light range.

The space 134 for storing the coolant is preferably filled with the coolant. For example, when water is used as the coolant, it is preferable that the entire space 134 is filled with water. This is because when both a water layer and an air layer exist in the space 134, there is a possibility that a loss may occur due to scattering of light in the space due to the difference in refractive index between the layers. Therefore, although the coolant may be a mixture of two or more types, it is preferable that the refractive index in the space 134 is constant. It should be noted that the refrigerant may be liquid or gaseous. For example, water, glycols, HFCs (hydrofluorocarbons), carbon dioxide, etc. can be used.

[Second embodiment]
[Structure of Wavelength Conversion Member]
Next, the configuration of the wavelength conversion member according to the second embodiment of the present invention will be described. FIG. 6 is a schematic cross-sectional view showing an example of the wavelength conversion member according to the second embodiment. The wavelength conversion member 200 according to this embodiment includes a base material 110, a phosphor layer 120, and a cooling member . The configuration of the wavelength conversion member 200 is the same as that of the first embodiment except for the configuration of the cooling member 130, so only different points will be described.

Cooling member 130 has supply holes 212 for supplying coolant to space 134 and discharge holes 214 for discharging coolant from space 134 . The cooling member 130 is also connected to a supply pipe 216 and a discharge pipe 218 through which the coolant passes through the supply hole 212 and the discharge hole 214, respectively. Cooling member 130 cools substrate 110 or phosphor layer 120 by circulating a coolant through space 134 through supply pipe 216 and discharge pipe 218 .

By circulating the coolant stored in the space 134 in this way, the cooling effect can be further improved, and it is possible to cope with the increase in output of the light emitting element. The refrigerant may or may not be circulated. Supply tube 216 and exhaust tube 218 may be connected to a pump or the like.

ADVANTAGE OF THE INVENTION The wavelength conversion member of this invention can suppress the deterioration of the light emission performance by the temperature quenching of a wavelength conversion member, etc., even if it uses a light emitting element of a high output, and can suppress deterioration of a fluorescent substance.

[Structure of Light Emitting Device]
Next, the configuration of the light emitting device of the present invention will be described. FIGS. 7A to 7C are schematic diagrams each showing an example of a light-emitting device using the wavelength conversion member according to the first embodiment. FIGS. 7A to 7C show the light emitting device 300 using the wavelength conversion member 100. The light emitting device 300 uses the wavelength conversion member 200 of the second embodiment. good too. Light emitting device 300 includes at least wavelength conversion member 100 or wavelength conversion member 200 and light emitting element 310 .

The light-emitting element 310 emits incident light (excitation light) that excites the phosphor used in the light-emitting device 300 . The light-emitting element 310 that emits incident light that excites the phosphor can be selected according to the type of phosphor used in the light-emitting device 300. It is preferably blue, violet, or ultraviolet light that is compatible with the body. Moreover, since the wavelength conversion member 100 or the wavelength conversion member 200 used in the light emitting device 300 is suitable for high power applications, the light emitting element 310 is preferably a laser diode.

A light-emitting device 300 using the wavelength conversion members 100 and 200 can have the light-emitting element 310 arranged outside the cooling member 130 as shown in FIG. 7(a). As a result, contact between the light emitting element 310 and the coolant can be prevented, and the risk of deterioration and failure of the light emitting element 310 can be reduced. In such a configuration, wavelength conversion members 100 and 200 need to have at least a portion of the bottom surfaces of base material 110 and cooling member 130 translucent. The translucency in this case does not have to be translucency for the entire visible light range, and may be any property as long as the light source light (excitation light) emitted from the light emitting element 310 is transmitted.

A light-emitting device 300 using the wavelength conversion members 100 and 200 can have the light-emitting element 310 disposed inside the cooling member 130 as shown in FIG. 7B. As a result, the light-emitting element 310 is in contact with the coolant, so that the light-emitting element 310 itself can be cooled. However, in this case, since the light emitting element 310 needs to operate stably, the selection of the coolant may be restricted. In such a configuration, at least part of the substrate 110 of the wavelength conversion members 100 and 200 needs to be translucent. Translucency in this case may also be a property of transmitting the light source light emitted from the light emitting element 310 . 7A and 7B, the surface of the substrate 110 may be formed with a dichroic mirror coat that transmits light from the light source and reflects converted light.

A light-emitting device 300 using the wavelength conversion members 100 and 200 can have the light-emitting element 310 disposed on the substrate 110 side, as shown in FIG. 7(c). Thereby, the reflective light emitting device 300 can be configured. Since the heat generating point of the phosphor layer 120 is located far from the coolant, the reflective light emitting device 300 can be configured by lowering the temperature of the coolant or using the wavelength conversion member 200 according to the second embodiment. preferable.

In addition to the configuration described above, the light-emitting device 300 can use lenses, dichroic mirrors, prisms, display devices, projection optical systems, motors, and the like, which are not shown in the drawings, depending on the design.

The display device displays an image projected by the light emitting device 300 . A liquid crystal panel, a digital mirror device (DMD), or the like can be used as the display device. The projection optical system uses radiation light emitted from the wavelength conversion member 100 or the wavelength conversion member 200 to project an image displayed on the display device to the outside. The projection optical system consists of a plurality of lenses and adjusts zoom and focus.

ADVANTAGE OF THE INVENTION The light-emitting device of this invention can suppress the deterioration of the light emission performance by the temperature quenching of a wavelength conversion member, etc., and can suppress deterioration of a fluorescent substance, even if it uses a high-output light-emitting element. Such a light-emitting device can be used for laser lighting, laser projectors, and the like.

[Method for producing wavelength conversion member]
Next, an example of the method for manufacturing the wavelength conversion member according to the embodiment of the present invention will be described. The following manufacturing method is a manufacturing method of the wavelength conversion member according to the first embodiment. FIG. 8 is a flow chart showing an example of the method for manufacturing the wavelength conversion member of the present invention. First, a base material formed into a predetermined shape is prepared (step S1). The shape of the substrate may be a plate-like shape or a shape with concave portions formed on the surface.

Separately, phosphor particles and an inorganic binder are mixed to prepare a phosphor paste (step S2). First, phosphor particles having a predetermined average particle size are prepared. Various phosphor particles can be used depending on the design of the wavelength conversion member. Two or more types may be used. Next, the prepared phosphor particles are weighed, dispersed in a solvent, and mixed with an inorganic binder to prepare a printing phosphor paste having a predetermined viscosity.

A ball mill, propeller stirring, or the like can be used for mixing. The mixing time is preferably 3 minutes or more and 30 minutes or less in the case of a ball mill. In the case of propeller stirring, the time is preferably 5 minutes or more and 120 minutes or less. As a result, variations in the thickness of the phosphor layer can be reduced. High boiling point solvents such as α-terpineol, butanol, isophorone and glycerin can be used as the solvent. In addition, a filler made of an inorganic material may be added for the purpose of adjusting the viscosity of the phosphor paste and adjusting the filling property of the phosphor particles.

Also, the inorganic binder is preferably an organic silicate such as ethyl silicate. By using the organic silicate, the phosphor particles are dispersed throughout the phosphor paste, making it possible to produce a phosphor paste with an appropriate viscosity.

For example, when ethyl silicate is used as the inorganic binder, the amount of ethyl silicate is 70 wt % or more and 100 wt % or less, preferably 80 wt % or more and 90 wt % or less, based on the mass of water and the catalyst. In addition, the inorganic binder is obtained by reacting a raw material containing at least one selected from the group consisting of a silicon oxide precursor that becomes silicon oxide by hydrolysis or oxidation, a silicic acid compound, silica, and amorphous silica at room temperature, or , obtained by heat treatment at a temperature of 300° C. or less. When using a binder that is hardened by heat treatment, it is preferable in that the variation in the thickness of the phosphor layer can be reduced because the change over time at room temperature is small and the fluidity of the ink can be stably maintained. Silicon oxide precursors include, for example, those containing perhydropolysilazane, ethyl silicate, and methyl silicate as main components.

Next, a phosphor paste is applied to the surface of the prepared base material to form a paste layer (step S3). A screen printing method, a spray method, a drawing method using a dispenser, or an inkjet method can be used to apply the phosphor paste. A screen printing method is preferable because a paste layer having a uniform thickness can be stably formed. Screen printing is a method in which phosphor paste is pressed against a screen stretched on a frame with an ink squeegee. The thickness of the paste layer is adjusted so that it will have a predetermined thickness after firing.

Then, the applied raw material paste is heat-treated to form a phosphor layer (step S4). The heat treatment temperature is preferably 150° C. or more and 300° C. or less, and the heat treatment time is preferably 0.5 hours or more and 2.0 hours or less. Moreover, the temperature increase rate is preferably 50° C./h or more and 200° C./h or less. Also, a drying step may be provided before the heat treatment. When a drying step is provided, the drying temperature is preferably 100° C. or higher and 150° C. or lower, and the drying time is preferably 20 minutes or longer and 60 minutes or shorter. Through such steps, a phosphor layer is formed on one main surface of the substrate. In particular, when a nitride phosphor is used, it is desirable to perform the heat treatment in a non-oxidizing atmosphere such as nitrogen or argon in order to prevent deterioration of the phosphor due to oxidation.

Separately from the above steps, a cooling member is manufactured (step S5). It is preferable that the cooling member is formed in a bottomed opening shape having a space for storing a coolant inside. The cooling member may be formed of one member or may be formed of a plurality of members. A portion of the cooling member that needs to be translucent can be made of, for example, sapphire, glass, or the like. Moreover, a portion that does not need to have translucency can be formed of ceramics, metal, resin (composite resin containing filler material with high thermal conductivity, etc.), or the like. Further, a layer for preventing light transmission may be formed on the surface of the substrate having translucency.

Next, a coolant is injected into the space of the cooling member (step S6). As the refrigerant, for example, water, glycols, HFCs (hydrofluorocarbons), carbon dioxide, or the like can be used.

Then, the base material and the cooling member are connected (step S7). The connection method (fixing method or joining method) between the cooling member and the base material can be any method, such as screwing, clamping, or adhesive bonding, as long as it can prevent refrigerant leakage due to internal pressure. There may be. Gaskets such as O-rings may also be used. Moreover, you may use these together. At this time, if a liquid is used as the coolant, the connection should be made with care so as not to leave or mix gas in the space.

With such a manufacturing process, it is possible to manufacture a wavelength conversion member capable of suppressing deterioration of the light emission performance due to temperature quenching of the wavelength conversion member even when using a high-output light emitting element, and suppressing deterioration of the phosphor. .

[Examples and Comparative Examples]
(Preparation of sample)
(Example 1)
A disk-shaped sapphire substrate having a diameter of 30 mm and a thickness of 0.5 mm was prepared as a substrate. A raw material paste (phosphor paste) was prepared by weighing a YAG-based phosphor having an average particle size of 15 μm for a phosphor layer, α-terpineol as a solvent, and ethyl silicate as an inorganic binder, and mixing them with a propeller for 30 minutes. . The obtained raw material paste is applied onto a base material by screen printing so that the phosphor layer after heat treatment has an average thickness of 100 μm, and the base material after coating is dried at 100° C. for 20 minutes, and then an electric furnace is used. The temperature was raised to 150° C. at a rate of 150° C./h in a non-oxidizing atmosphere, and heat treatment was performed for 60 minutes. Thus, a substrate having a phosphor layer on one main surface was prepared.

The following members were prepared as members constituting the cooling member. A disc-shaped sapphire having a diameter of 30 mm and a thickness of 0.5 mm was prepared as the first member constituting the bottom surface. In addition, as a second member constituting the side surface, a rectangular parallelepiped hollow member having a length of 50 mm, a width of 50 mm, a height of 30 mm, and a thickness of 5 mm is provided. A member made of resin (PEEK) and having an opening with a diameter of 20 mm was prepared.

The first member and the O-ring were placed in the depression of the opening of the lower surface of the second member, held by a ring-shaped aluminum thin plate and screwed. After that, pure water is injected as a coolant into the inside of the cooling member, and a base material provided with a phosphor layer and an O-ring are placed in the recess of the opening of the upper surface of the second member, and a ring-shaped aluminum thin plate is placed. I held it down with the screw and fixed it. At this time, the base material was arranged with the main surface provided with the phosphor layer facing outward. Thus, the wavelength conversion member of Example 1 was produced. The wavelength conversion member of Example 1 has a schematic cross section as shown in FIG. 9(a). FIGS. 9A and 9B are schematic cross-sectional views showing wavelength conversion members of examples, respectively.

(Example 2)
A wavelength conversion member of Example 2 was produced in the same shape and the like as in Example 1, except that a metal (aluminum) member was used as the second member. The wavelength conversion member of Example 2 has a schematic cross section as shown in FIG. 9(a).

(Example 3)
A supply hole for supplying the refrigerant and a discharge hole for discharging the refrigerant are provided on the opposite side surfaces of the second member, and pipes with an inner diameter of 6 mm (supply pipe and discharge pipe) are connected to the supply hole and the discharge hole, respectively, to pump A wavelength conversion member of Example 3 was produced in the same shape and the like as in Example 2, except that it was connected to . The wavelength conversion member of Example 3 has a schematic cross section as shown in FIG. 9(b).

(Comparative example)
The substrate itself having the phosphor layer of Example 1 was used as a wavelength conversion member of Comparative Example. That is, the wavelength conversion member of the comparative example is a wavelength conversion member provided with no cooling member. The wavelength conversion member of the comparative example has a schematic cross section as shown in FIG. FIG. 10 is a schematic cross-sectional view showing a wavelength conversion member of a comparative example.

[Evaluation of Wavelength Conversion Member]
The wavelength conversion members of Examples and Comparative Examples were left at room temperature of 20°C for a while so that the temperature of each part including the coolant reached 20°C. Then, the wavelength conversion members of Examples and Comparative Examples were irradiated with a blue laser beam having a wavelength of 445 nm at an output of 2 W, and the maximum temperature on the surface side of the phosphor layer was measured using a thermo camera after 10 seconds and 1 minute. , confirmed after 3 minutes. In Example 3, while the refrigerant (pure water) was discharged from the discharge hole at a rate of 30 ml/s, the refrigerant of 20° C. was supplied from the supply hole at the same rate.

The temperatures measured by the thermo camera increased in the order of Example 3, Example 2, Example 1, and Comparative Example. In the comparative example, the temperature after one minute exceeded 200° C., which is a temperature at which temperature quenching of the phosphor may occur. On the other hand, in Examples 1 to 3, the temperature after 1 minute is stabilized in the range of 80° C. to 150° C., which is sufficiently lower than the temperature at which temperature quenching of the phosphor may occur. However, no temperature increase was observed. That is, the wavelength conversion member of the example suppresses the temperature rise of the phosphor layer compared to the wavelength conversion member of the comparative example, and suppresses temperature quenching even under high-energy excitation conditions that may cause temperature quenching. It was confirmed that a high amount of luminescence was obtained.

Based on the above results, the wavelength conversion member of the present invention can suppress deterioration in light emission performance due to temperature quenching of the wavelength conversion member even when a high-output light emitting element is used, and can suppress deterioration of the phosphor. was confirmed. Moreover, it was confirmed that the wavelength conversion member of the present invention can be suitably used for light emitting devices such as projectors.

It goes without saying that the present invention is not limited to the above-described embodiments, but extends to various modifications and equivalents within the spirit and scope of the present invention. Also, the structure, shape, number, position, size, etc. of the constituent elements shown in each drawing are for convenience of explanation, and may be changed as appropriate.

100, 200 Wavelength conversion member 110 Base material 112 One main surface 114 The other main surface 120 Phosphor layer 122 Phosphor particles 124 Translucent ceramics 130 Cooling member 131 First member 132 Second member 134 Space 136 Opening 140 O-ring 212 Supply hole 214 Discharge hole 216 Supply pipe 218 Discharge pipe 300 Light emitting device 310 Light emitting element

Claims (6)

A wavelength conversion member,
a substrate formed into a flat plate;
a phosphor layer provided on one main surface of the base material and formed of phosphor particles and translucent ceramics;
a cooling member provided on the other main surface of the base material and having a space for storing a coolant therein;
The wavelength conversion member, wherein the cooling member cools the base material or the phosphor layer by bringing the coolant into contact with the other main surface of the base material. 2. The wavelength conversion member according to claim 1, wherein the base material has translucency. The cooling member comprises a first member forming a bottom surface facing the base material and a second member forming a side surface connected to the base material,
3. The wavelength conversion member according to claim 2, wherein at least a part of said first member is translucent. The cooling member comprises a first member constituting a bottom surface facing the base material and a second member connected to the base material and constituting a side surface,
4. The wavelength conversion member according to claim 2, wherein the second member does not have translucency. The cooling member has a supply hole for supplying the coolant to the space and a discharge hole for discharging the coolant from the space, and the supply hole and the discharge hole are provided with a supply pipe and a discharge pipe through which the coolant passes, respectively. is connected and
5. The cooling member cools the substrate or the phosphor layer by allowing the coolant to flow through the space through the supply pipe and the discharge pipe. A wavelength conversion member as described. A light-emitting device,
a wavelength conversion member according to any one of claims 1 to 5;
and a light-emitting element provided on the other main surface side of the wavelength conversion member and emitting light having a wavelength within a specific range.

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